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When the 1.9s were new they came with 15w-40 non synthetic oil. BMW was using Valvoline then. They later switched to Castrol 5-30 synthetic, I think in 1999. I have been using Royal Purple 15w-40 for the last 150k miles. I do live in Texas so I use it year around, you might want a thinner weight if you drive in the cold. But what you are reading is correct, although you will use 5 qts to get to the full line.

My expirience with 1998 Z3 1.9L is that Pentosin 5w30 runs cleaner without consumption. Only has 58k miles; but tried Mobile 1 twice. Each time I consumed 1 liter per 1000 miles with an increase in upper valve / cover varnish. Each time I switched back to Pento the consumption stopped, and the deposits went away. FL. driver, mixed highway, slow beach cruzin.. Tried Pento as recommended by German / Turkish shop owner / tech in Tampa....he was right......at least for my Z.

97 z3 1.9L... Im planning on changing my oil on the car. Im reading that it takes 4.7Q of 15W-40 and that just sounds wrong to me. what do you guys think? and what do you guys use?

I just bought the same car from a BMW dealer and had them change the oil. They put in BMW synthetic 15W-40, which is what they said it takes. I really don't think it matters much, especially the way I drive, and plan to do the next oil change myself at 5K miles out of the stock of synthetic 5W-30 that I use for our other cars.

5-30 Mobil 1 every 5K miles, but now every 10K miles. 144K miles on engine. When I had the valve gaskets replaced, the BMW dealer tech said that's the cleanest engine he has seen. 5 qts of Mobil 1 at Walmart for about $26, like one post said sometimes they are on sale.

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AFAIK BMW doesn't make a 15W-40 synthetic. Their current oil for almost every BMW is a full synthetic 5W-30. The oil caps of the older cars say 15W-40, but that was a conventional oil.

I use the BMW 5W-30 in our Roadster, basically because with the BMW CCA discount, it is one of the cheapest full synthetics out there. I use Mobil 1 in two of our other cars (M3 LTW and Jeep Grand Cherokee). Castrol TWS 10W-60 in the E46 M3 because that is what is speced.

Most of our vehicles get the oil changed every year, as the mileage is not enough to trigger the change.

And I do see from a bulletin that it is mineral oil, not synthetic:
"... SAE 5W30 BMW High Performance Synthetic Engine Oil is formulated with
advanced additive technology to meet BMW specifications required in line with our
extended service intervals. As such this is the only oil to be used in conjunction with
the BMW reimbursed maintenance program.
07 51 0 017 866 5W30 Synthetic
07 51 0 017 868 15W40 Mineral..."
BMW NA Bulletin 11 01 01 dated 03/01

My 1997 1.9L oil cap does not say anything. The Owners Manual does say 15W-40 above 15ºF, and does not mention synthetic.

i dont think anyone makes 15w-40 full syn. you can find 5w-40 full syn, which flows better when it's cold. In theory and lab testing, synethic oil is better than conventional. It maintains its grade longer, at higher temp, it evaporates less, and flows better. However, in the real world unless your car is designed for syn oil, it doesn't mean that your car encounters extreme conditions where it can take advantage of these benefits. thus, no one can truly make the claim that synthetic is "better" for your car.

overall, 15w-40 is a good grade, and you have lots of options, such as Shell Rotella, Chevron Delo, Mobil Delvac....etc